1. Field of the Invention
The present invention relates to control systems and methods for manipulators and more particularly to a control system and method for improving servo loop response by sythesizing feedback signals and utilizing load modeling to provide resolved compliant motion control.
2. Description of the Prior Art
The speed of servo loop control systems for manipulator apparatus having a manipulator arm movable in a plurality of axes or joints depends upon the bandwidth of the control loops for the joints. Since manipulators, especially those with high load ratings, have a very low first antiresonant structrual frequency, the response of these control systems and thus the speed for stable operation is limited to relatively low values. The use of a torque loop and pressure (hydraulic) or current (electrical) feedback and inertia scaling have improved the stable response of manipulator apparatus for example as discussed in U.S. Pat. No. 4,362,978.
Since it would be desirable to achieve faster response and operating speeds, assuming that the mechanical design is optimized, the only other possibility is to improve the control system.
One approach would be to utilize feedback signals from points or joints of the manipulator arm that provide increased bandwidth. However, due to the complex nature of joint or axis interconnection and structural members, these feedback signals are both theoretically and practically difficult to obtain either by computation or measurement.